Want to be a homicidal maniac hopped up on biotoxins in an upcoming Hollywood horror flick? Who wouldn't? It'll cost you, via an eBay auction for a walk-on role, but the cash you fork over will go to a good cause: Greenpeace. The connection's a bit tenuous between the remake of the '70s George Romero cult classic The Crazies and the well-known environmental organization. See, the original movie centered on a biological weapons spill in small-town America, the effect it had on the townsfolk (really, really not good) and the military's (unsuccessful) attempts at containing it. The remake, starring Timothy Olyphant, involves a contaminated water supply. There's a stronger link, though, between the new film's producers and pro-social causes. Participant Media, which is producing with Overture Films, is home to a steady stream of message movies like Fast Food Nation, An Inconvenient Truth, Syriana and Standard Operating Procedure. The remake, directed by Breck Eisner, is one of the company's first forays into genre filmmaking. The winner of the eBay auction will travel to the Iowa shoot to play one of the infected residents, adding a conversation starter to the old résumé and earning some Earth-friendly karma points in the bargain.